Frank a



(No Model.)

P. A. PICKERNELL.

TELEPHONE COMBINATION GIROUIT.

No. 405,677. Patented June 18, 1889.

Winessea.

I Inn/670607 N. PETERS, wmmuw her, Washington. v.0.

UNITED STATES PATENT OFFICE,

FRANK A. PIOKERNELL, OF EAST ORANGE, NEWV JERSEY, ASSIGNOR TO THE AMERICAN TELEPHONE AND TELEGRAPH COMPANY, OF NEV YORK,

TELEPHONE COMBINATION-CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 405,677, dated June 18, 1889. Application filed March 13, 1889. Serial No. 303,088. (No model.)

To all whom it may concern.-

Be itknown that I, FRANK A. PIOKERNELL, residing at East Orange, in the county of sex and State of New Jersey, have invented certain Improvements in Telephone Combination-Circuits, of which the following is a specification. V

For the more perfect and undisturbed transmission of speech it is a well-known practice to provide a return-xvi re for the telephonecircuit instead of utilizing the earth therefor. A metallic or double-wire circuit is thus formed, the direct and return wires whereof are substantially equidistant from any external electric wire. Disturbing induced currents are inthis way neutralized and earth-cm'rents avoided. For long distaneesfor example, between large cities this, so far as I am aware, is the only practically satisfactory plan of construction; but since metallic circuits require twice as much wire as earth-return circuits, it is clear that they are very expensive; moreover, in the majority of cases the sub-station lines are already in operation upon the single-wire plan,

and for these reasons the lines extending be tween different centers of population should in all cases be constructed as metallic circuits, as the major partbf the disturbance originates upon the said long stretches of line. In many cases it is also desirable to utilize fortelephone-exchange substation circuits, if feasible, the single-wire or earth-re turn plan of construction, and thereby to keep the cost down, provided that this can be done without sacrificing materially the advant-ages'accruing from the use of metallic circuit.

My invention accomplishes this, and its object is to arrange single-wire telephone-circuits in such a way that each one may be enabled to utilize some other as a return-wire for itself extending to the same central station, the two together constituting a temporary metallic telephone-circuit Any number of ground-return or singlewire circuits may thus be enabled at an inconsiderable expense to participate in'the benefits of a non-induct ive parallel metallic circuit, and in case any sub-station on a single line is to be connected with a substation at a distance by means of a metallic trunk-circuit, my invention furnishes a means whereby this may be done, and whereby the two wires of the said trunkcircuit may be made practically continuous through the said sub-station directly and without the intermediation of repeating-coils.

My invention is shown in the drawings as being embodied in two ordinary single-line telephone-circuits, which are paired with each other to form a metallic circuit when either sub-station desires to use the line for conversation; but it is obvious that any number of a such lines may be so arranged.

The several sub-station earth-return circuits are arranged in pairs; but each is capable of being connected singly at the central station with any other similar ci rcu'it, as usual, while the two wires of the said pair running to two subscribers stations near to one another are used together by either of the said stations as a metallic circuit. This arrangement provides that either party while talking has a metallic circuit; that the central station can ring one subscriber without ringing theother; that when one subscriber is using the circuit in conversation, the other one, should he attempt to ring, is at once apprised that the joint-talking line is already in use; that the telephonic service is absolutely prirate; that the circuit does not.- include electrosmagnets with their well-known retarding effect, while it does not necessitate any complication or material difference in the operation of the central station. To these ends my invention comprises a circuit arrangement of a pair, and necessarily therefore of any number of pairs, of single wire circuits, in which each wire of the said pair or pairs is when quiescent terminated at the earth at its own sub-station, as usual, and is capable of being united at a central station with other single-wire circu ts, while, 110wever, itis also capable of being employed as one member of ametallic circuit of which the other wire of the pair constitutes the other member, the two lines then forming a metallic circuit adapt-ed to be used at will, albeit separately, by the sub-station of either of the said lines which are respectively its compo- 10o nent parts, the said metallic circuit being also adapted to be united at the central station with any other metallic circuit similarly or otherwise formed.

It furthermore consists'in two lines, each extending from a central stationto its own sub-station and there normally grounded, but

each passing first through a contact controlled by the automatic switch device of the other, whereby each sub-station may obtain the control of both lines for conversational purposes and at the same time break the continuity of the calling-circuit of the other, thus preventing either station from sending call-signals while the other is using the line and affording an indication also atthe station essaying to call by the refusal of its bell to ring that the said other station is already using thei line. it consists, also, in establishing the; telephones 'at one of the said sub-stati'ons in a normal -open branch circuit permanently attached to the line leading to the other station. At a point before the said line reaches the controlling automatic switch contact,

whereby,when the said switch at either sub- 2 station is, by therem'oval of the receiving-i telephone, permitted to act, the said tel'e-E phones may be and are included in a circuit composed of both lines, the normal circuit of the line leading to the other station being" broken and the said other station being thereby disabled from sending call-signals until the receiving-telephone is replaced.

Itaiso comprises suitable means for bimgnrerwosub tations or two lines so paired to -signal"and communicate telep'lion:

many with each other, and in certain other details in mean-augment ofthe spring-jacks j and central-station devices, to be hereinafter more fully specifiecl.

thedrawings', which accompany and'for'm a part'of this specification, Figure 1 is a general electrical diagram indicating an arrangemeat of circuits and 'ins t'rumentalities in which have actually embodied my 'inve'ntion, and 'Fig. 2 shows the actual position of the fourf's'pringjacks sockets of two paired grdnn'dedcircuits. I p I Referring now more specifically to 'thesa'id drawings, X fla 'irese nts a central station and 29 and 31 are s'ub stations at some distance therefrom and near to one another.

The spring-jacks ll maybe I the said contact-screw, but so disposed that it may be lifted out of contact therewith by the insertion of a properly-conformed plug in the socket. The annunciators are also of the ordinary character. Now, considering the line B, the circuit may be traced from thepoint Where it enters thecentral station, as follows: Line B, spring 3, and contact-screw x of springjack J wire 1), including the electro-magnet of the annunciator a of station 29, contactscrew 0c, and spring 8 of spring-jack J Wire 17', and ground-wire g to earth E. Similarly, line D, entering the central stat-ion, may be traced by way of spring 3 and contact-screw 00 of spring-jack J wire d, including annunciator a of station 31, contact-screw w and spring 8 of jack J and ground-wire d to earth at E.

The spring-jacks of each pair of lines are mechanically disposed, as shown in 2, where the plug sock'ets l and 2 of jacks J 2 and "J are at a determinate distance ina vertical plane, While the sockets 3 and 4 "of the second line of the pair are disposed in a like vertical plane immediately adjacent to the sockets of the first line. Furthermore, it is required that the distance between 1 "and 2 and between 3am l shallbe equal to that between 1 and 3, because the same doubleplug connector thatis adapted to fit a pair of sockets-say 1. and 2verti'c'ally mounted must be also capable of being thrust into 1 and 3, for the purpose of operating the two lines together as-a metallicc'ircui't. This plugco'nnecto'r P'i's shownas'consistin'gof two sim- 'ple'cond'u cting-plugs '19, h'avin'g-acom mon "nonconducting handle R- This may, as shown, be affixedto one end of a do'i'ible cfonducting cord 0, provided at its "other end with similar compound plug P, having twin plugs 19 for insertion in adjacent plug-sockets, the main cord c at both ends being' bifurcated to the v several'simple plugs by brancl1es"ca'nd c Such-a "compound plug and cord "conductor may be used either, as-shown, to connectoue of the lines-of a pair with a metallici'circuit, or it may be employed to connect the two lines of a pair in the same wa y witha inetallic circuit. v

It is notabsolutely necessary to efirployitwo spring-jacks for each line, but it is useful in mixed systems of metallic and single w'ire circuits, because when they are present the double-conductor cords'andi plu-gs '"can be used for all circuits alike and two classes of cords dispensed with. The cord "0 canfof "course-be fitted to unite theseveral lines Dor B with calling appa ratusjand operators telephones'in a "manner well "understood, thesaid 'callin'gapparatus being, if desired, included in the'circuitof said cord. 4 p

M and N represent two "metallic {trunk-line circuits terminating 'atcent-ralstation X and adapted to be there united with'anysub-station line or with each .other. The two wires of each m m and n n are respectively connected with connecting and calling devices ceiving telephones.

H and H are the automatic switch-hooks, operated, as usual, by the removal and replacement of the receiver.

G and G are the bells and generators, c i the respective transmitter-batteries, and K and K keys, the object whereof will presently be stated.

Suppose, first, the receivers to be in place and resting upon the hooks H and H. Each line coming from' the central station is run first to the station of the other. There it passes through a pair of contacts (preferably sliding) y v,controlled by the movement of the automatic switch at the saidstation of the other line, but carefully insulated from the said switch. From the contact Q) it continues to its own station, where it connects in the ordinary way at S with the automatic telephone-switch H. The receivers being in place upon their hooks, the circuit continues through the substance of said hooks to the resting-contacts thereof 2, and then through the bells and generators G to earth. Under these conditions the central station can of course by means of the ordinary calling apparatus signal either substation over its own earth-circuit, and each sub-station can also in like manner signal the'central station.

Although the letters in the drawings referring to like parts are distinguished from one another bybeing at one station provided with indices, I have not thought it necessary to refer to the said index letters or figures, since both lines are constructed identically.

Now, suppose one of the sub-stations (say 31) to be using the two lines as a metallic circuit, the telephonereceivenjs of course re-' moved from its support, as shown. The circuit from the central station, by way of wire D,is then the same as beforeuntil thepoint S on the switch H at station 31 is reached but the said switch now being in position for talking, the circuit continues, by contact-spring 21, wire 20, transmitter T, wire 19, receiver 73, wire 18, to a point 17, where the telephone branch, normally open at 21, is permanently united with the main line B of the other station, and from this point the circuit returns over said line B to the central station, the resting or calling circuit of said line being broken at y by the elevation of switch I-I. Now, as the plug-sockets at the central station are arranged, as in Fig. 2, in the form of a square, the operator can by inserting his twin plugin sockets 1 and 3 connect the two lines B and D with any other metallic circuit, thus constituting a compound metallic circuit extending to station 31.

Both stations of course have the same facilities, and either can get possession of the line for use as a metallic circuit at any time except when the other is actually so using it. The .stations of grounded lines can thus at low cost be furnished with metallic circuit facilities, and when so working no earth branch at all is in connection with the said metallic circuit.

It is impossible that either sub-station can interfere by sending a call-signal while the other is conversing, because the calling-circuit of the second station is broken in the switch of the first, and it is equally impossible that one station can overhear the conversation of the other, becausewhen one is already using the line, should the other remove his receiver and attempt to listen, the only result thereby attained is that the circuit of the first is broken in the switch of the second.

Another advantage is that by this arrangement no electro-magnets are left in the talking-circuit to retard and interfere with the voice-currents.

The central station rings each independently by using the plug-sockets 1 and 2 to ring station 31, andsockets 3 and 4 to ring station29. Neither station is therefore disturbed by hearing call-signals intended for the other. 0

' When it is desired to connect either line as a single circuit with other single lines at the central station, this can readily be done by employing the spring-jack J 2 of line D or J 4 of line B only. The talking-circuit for sta-v tion 29 would in that case start at the central? station earth terminal, and passing over line D would continue over line D, telephones and -switch-hook. at station 29, contacts 1; and y, at station 31, and then over line B to springjack J which, by means of any suitable single cord and plug connector, can be united to a like jack of the line desired. I havethus shown the adaptability of my system of combined circuits to metallic or single-wire circuitfwork. it is only requisite now to describe the means whereby the two sub-stations of any pair can signal and converse with each other. K is a compound key located at station 31, and K isa similar key located at station 29, both being arranged to control both circuits. the space between the two stations. Line B, after passing the contacts y o controlled by but insulated from switch H at station 31,'is led on its way to station 2-9 through the lower contacts h k of-key K, then by wirebfto back contact of thekey K, to the upper strap 0 thereof, and from thence to the switch'H at S. Line D in the same way reaches the switch H at station 31 by way of wiresd C1 and (1 the lower contacts h and k of .key K, and the upper contacts land 00f key K. The telephones of both stations being at rest,

A portion of each line traverses IIO ing the key, thus breaking both normal con tacts and forming a new one between the upper strap of the key and that member of the original lower contactwhich leads to the other station. Let station 31, for example, signal station 29, Theoperator presses the key K and turns the crank of his generator. The rin gin gcircuit is now from E at station 31, through wire w, generator and bell G, spring-contact z, hookswitch 11, wire d upper key-strap 0, middle key-strap e, fixed key contact-piece wire I), back contact Z of key K, upper strap of said key, wire b switch H, bell-contact spring 2', and bell G to earth. Each subscriber can thus signal the station on the other line of his pair without first calling the central station, and the operator at the other station 29, hearing the call, may press his key K, take his receiver from the ho.ok,-and talk, station 31 now leaving key K undepressed. A local talking-circuit is thus formed, extending from earth at the central station through springjack J annunciator a, wire d, jack J linewire D, junction-point 7, receiver 23, and transmitterT, at station 29, wires 8 and 9, contact-spring 10, switch-bar H, wire 19 upper key-strap 0'', central key-strap e, fixed contact-piece k, wire d, contacts Z and 0. of key K, switch-bar I-I, contact-spring 21, wire 20, transmitter T, wire 19, receiver 6, wire 18, junction-point 17, and then by line B back to earth at the central station. It is sometimes undesirable to form a circuit of this length simply for telephonic communication between these subsstations, and other modes of arranging the circuits may be substituted. For example, I have indicated one which is very convenient.

A switch L or L may be introduced into the circuit of each main line external to the junction of the telephone branches. Normally these. switches may rest on the.p.oints inbefore described, of two single-line or earthreturn circuits, each extending'from a central station to its own sub-station, and there norj mally grounded after passing through signal- 1 ing devices, but each passing first through a circuit breaker or movable. contact controlled it 11. and thus maintain the continuity of said lines; but if private telephonic communication be desired, the switches may be turned onto points to and 14 which .are respectively the terminals of normallydiscontinuous branches 25 and 26, extending .from the wires (1 and b and a short telephonic circuit may thus be formed, which is completed when both receivers are taken from their holders. Neither key need now be pressed during conversation.

Keys with back and front contacts may of course be substituted for the switches L and L.

Having now described my invention and its 3 operation, I claim 1. In a telephone-exchange system,two single-line or earth-return circuits, each extending from a central to a sub station and each normally grounded through signaling apparatus at its own sub-station, combined with automatic switches at each sub-station controlling the earth terminals of both lines and operated by the removal and replacement of the receiving-telephones, whereby when the said receiving-telephone at either sub-station is removed from its position. of rest it is connected in a metallic circuit formed of the said two lines, and whereby the normal earth terminals of both lines are automatically disconnected by the operation of the switch at either. station.

2. In a telephone-exchange system, the combination, substantially as hereinbet'ore described, of two single-line or eartlrreturn main circuits, each extending from a. central station to an earth terminal at an independent sub-station, and signal sending and receiving appliances at each sub-station included in said circuit, with telephones at eachsub-station, and. means also at each sub-station for disconnecting the earth terminals and signaling appliances of both circuits, and for automatically uniting the said two single lines to establish a metallic circuit including the said telephones, whereby each sub-station may be provided with an individual ringing-line,

and with an exclusive metallic talking-circuit, for the purposes specified.

3. In a telephone system, two single-line or earth-return circuits, each extending from a central station to a sub-station, where it normally terminates in the earth, each line constituting a distinct and independent signalingcircuit, automatic devices at each sub-station operated by the removal and replacement of the telephone, whereby the said two distinct lines may be united through the telephones of said sub-station in metallic circuit, and spring-jacks at the central station arranged in pairs, as shown and described herein, the

' terminals of both lines at said central station I being in close proximity to each other, wherel by both terminals may by the same movement be connected with the terminals of any I other line, substantially as described.

4:. The combination, substantially as hereby the automatic switch of the other sub-station, for the purposes specified.

5. In atelephone-exchange system, the combination of two lines, each extending from a central station through the sub-station of the other to a normal earthterminal at its own sub-station, a normally-open branch circuit at each sub-station, including the telephones of the said sub-station, the said branch being in permanent connection at one end with the line of the other sub-station, as described, and automatically-operated means at each station for disconnecting the earth terminals of both lines, and for connecting the disconnected terminal of its own line with the normallyopen end of the telephone branch, whereby a metallic circuit including the telephones is established, substantially as hereinbefore described.

6. In combination with two telephone-lines,

IIO

and converse with each other Without the intermediation of the central station, substantially as specified.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing Witnesses', this 6th day of March, 1889.

F. A. PICKERNELL.

Witnesses:

JOHN A. BARRETT, GEORGE E. CoMYNs. 

